The present invention relates to gas turbine engine guide vanes. In particular, the present invention relates to gas turbine engine guide vanes that in use, are arranged in tandem, i.e. two stages of guide vanes are arranged adjacent each other in axially spaced relationship, in a gas turbine engine turbine system, there being no rotary turbine stage between them. The downstream stage of guide vanes is rotatable about the turbine system axis, relative to the adjacent upstream stage. Just such an arrangement, with benefits accrued thereby, is described, illustrated and claimed, in UK patent application 0002257.4 filed by the applicant for a patent for the present invention.
The present invention seeks to provide an improved arrangement of tandem mounted guide vanes.
According to the present invention, an arrangement of relatively rotatable stages of guide vanes mounted in tandem for use in a turbine system comprises a first stage of guide vanes having respective outer end shrouds, each of which includes at least one radially outwardly extending land portion on its outer surface, and a second stage of guide vanes having respective outer end shrouds, each of which includes at least one radially inwardly extending land portion on its inner surface, so that on assembly of said first and second stages of guide vanes in axial juxtaposition in a turbine system, the at least one inwardly extending land on each second stage guide vane lies upstream of an adjacent outwardly extending land on a respective first stage guide vane, so that on said guide vanes being subjected to gas loads during operation in a gas turbine engine, the second stage of guide vanes moves in a downstream direction and causes said lands to abut each other and thus provide a gas seal.